1. Field Of The Invention
Electron multiplier channel plates and method of making same.
2. Description Of The Prior Art
Glass multi-channel plates used to produce electron multiplication in image intensifier devices and the like are commonly formed of lead containing glasses which are treated in a reducing atmosphere at high temperature to produce lead-enriched surfaces along walls of the channels. These surfaces serve both as electrical conductors and secondary electron emitters for electrons colliding with walls of the channels during acceleration therethrough.
In rendering such plates readily adaptable to being secured within glass envelopes of image intensifier tubes and the like and also readily adaptable to the reception of electrode contacts on opposite faces thereof within such tubes, it is highly desirable that the channel structure of such plates be supported within and by a solid glass annulus. Thus, the annulus may be used as means for connecting the plate to side walls of an electron tube envelope and also as means for receiving electrode contacts without such contacts being in a position to interfer with electron transmitting channels and/or other elements within the electron tube.
Heretofor, however, treatment of a channel structure formed entirely of a high lead content glass in a reducing atmosphere at relatively high temperature has been found to produce the adverse effects of shrinkage of the channel structure as a whole and lowering of its expansion coefficient. These effects being caused by the removal of oxygen from the glass as its lead oxide is reduced, set up stresses at the boundary of the channel structure and a solid glass annulus or other such means within which the structure may be supported. If the stress is not sufficiently great to cause a breakage between the channel structure and glass annulus, as is frequently the case, it is generally sufficient to render the resulting microchannel plate extremely fragile and subject to breakage during its placement within an electron tube envelope and/or during subsequent use thereof in the tube.
The present invention relates to improvements in electron multiplier channel plates having outer glass annuli wherein greater stability and strength of structure is afforded.